The present invention relates to an electronic watch of the type using touch-sensitive keys or key switches for selecting and controlling the watch functions.
Touch-sensitive or contactless key switch devices are now used to replace the conventional push-button contact switch systems used for selecting and controlling the functions of an electronic watch such as time setting, switch on and off the chronograph function, etc. Known touch-sensitive key switch devices include a transparent electrode disposed on the inner face of the crystal of the watch and permanently connected to the oscillating circuit or the frequency divider of the watch. A circuit is provided to use the signals which are produced when the user puts his finger onto the crystal opposite the electrode.
A number of keys (two or three) are often provided in the watch. As the keys are permanently energized, the power consumption is relatively high and, consequently, the lifetime of the watch battery is substantially reduced.
Accordingly, it is an object of the present invention to reduce the consumption of current in watches using touch-sensitive keys.